Bed-in-a-bag sets vary widely from company to company, but most sets include a comforter, pillow shams, a bed skirt and a sheet set. Sets on Wayfair.com, for instance, include anywhere from five to 24 pieces.
Searching for "bed in a bag" on many retailers' sites brings up results for all bedding sets, not just sets the manufacturer specifically markets as a bed in a bag. This means that in addition to sets that have a fitted and flat sheet included, there are also sets which only include the decorative items of a bedding set. Overstock.com's product names tend to make it clear if sheets come with a given set. Sets without sheets are usually referred to as comforter sets.
A twin bed in a bag set typically includes fewer pieces than a queen set. A king set normally includes more items in the bag than any other size. For example, a twin set in one style might include a comforter, fitted sheet, flat sheet, pillow case, sham and bed skirt, while the king set of the same style might include a second pillow case and sham.
Some of the largest sets, regardless of whether or not they include a sheet set, include additional items such as European shams, decorative pillows and even curtains.